As one mode of a conventional traveling vehicle, there has been known a traveling vehicle in which power can be transmitted from a continuously variable transmission device for turning which is interlockingly connected with an engine to a power transmission system for turning which is disposed in the inside of a front transmission part, while power can be transmitted from a continuously variable transmission device for traveling straight forward which is interlockingly connected with the engine to a power transmission system for traveling straight forward which is disposed in the front transmission part by way of a rear transmission part, and these powers of the power transmission system for turning and the power transmission system for traveling straight forward are combined by a planetary gear mechanism which is disposed in the front mission part, and a resultant force is transmitted to left-and-right-side drive wheels respectively.
Then, a PTO shaft is interlockingly connected with the rear transmission part by way of a PTO transmission part, and a power transmission system for PTO is disposed in the PTO transmission part so that the speed of the PTO shaft can be changed in plural stages due to the power transmission system for PTO.
Further, a parking brake is provided to the outside of the front transmission part.
However, in the above-mentioned traveling vehicle, the front transmission part, the rear transmission part and the PTO transmission part are respectively formed as separate bodies and hence, it is necessary to provide transmission means such as transmission shafts for interlockingly connecting these transmission parts with each other and hence, time and efforts are necessary for an operation to interlockingly connect these transmission parts and, at the same time, it is difficult to arrange these transmission systems in a compact manner as a whole.
Further, since the parking brake is provided outside the front transmission part, it is necessary to provide a protective cover to protect the parking brake from splashed mud, soil and the like.
Further, while a steering wheel is interlockingly connected with the continuously variable transmission device for turning by way of an operation mechanism for turning, a forward/backward traveling changeover lever is interlockingly connected with the transmission device for traveling straight forward by way of an operation mechanism for traveling straight forward. The continuously variable transmission device for turning is operated by a steering wheel by way of an operation mechanism for turning and, at the same time, the transmission device for traveling straight forward is operated by the forward/backward traveling changeover lever by way of the operation mechanism for traveling straight forward thus enabling a given steering operation.
However, in the above-mentioned traveling vehicle, when the respective transmission devices are operated using the steering wheel and the forward/backward traveling changeover lever, an operator receives an operation load from the respective transmission devices or a reverse load (a so-called kickback) acts on the respective operation mechanisms due to a load applied to the respective transmission devices. Accordingly, the operator cannot perform the swift and light operation thus giving rise to a drawback that the operator easily becomes tired.